Yeah the general rule is higher the frequency, higher the data density, so the higher bandwidth, with a loss of range. But for drone use we do not need the higher bandwidth, we're only interested in range. Which means all things being equal, 5ghz is worse than 2.4ghz. Things become confused due to more likely interference on 2.4g & also SRRC countries that allow the higher FCC power outputs in 5ghz, but the lower CE power output on 2.4g.
Hi,
You are correct the higher the bandwidth the higher the signal to noise ratio (stronger signal) has to be. However, this is not the reason that 2.45GHz is better than 5GHz, it is just down to loss. I doubt very much that DJI use a different bandwidth on the different bands, there wouldn't be any advantage. I suspect they use 20MHz bandwidth on both.
5GHz has much higher path loss;
5GHz has greater loss from foliage and buildings;
5GHz has higher loss from rain and snow;
The antennas are generally higher gain at 5GHz leading to a smaller beamwidth (you need to be a little more accurate where you point the controller).
5GHz is said to 'scatter' whereas 2.45GHz 'penetrates' (and becomes absorbed). Scatter is not good for a line of sight transmission system.
5GHz does have a couple of advantages, the noise is generally lower (it is signal to noise which matters, not signal strength) and the channels do not overlap. meaning less interference from other users.
If you have Bluetooth and wifi turned on in your phone then you are creating some local noise right next to the antennas on your controller. I have had to turn these off before (especially Bluetooth which operates at 2.45GHz).
In open sites 2.45GHz will out perform 5GHz every time, the noise out of built up areas is usually low on both bands. However, in the city or areas of lots of wifi, then 5GHz might be the better choice, although watch out for trees, bushes, buildings etc.
